Apellis Pharmaceuticals recently announced that its complement factor C3 inhibitor, pegcetacoplan, beat the current standard of care for paroxysmal nocturnal hemoglobinuria (PNH) in a head-to-head Phase III trial.
Alexion Pharmaceuticals currently dominates the PNH market with its blockbuster drug Soliris (eculizumab), so demonstrating that pegcetacoplan was better than Soliris in this trial could prove crucial in enabling pegcetacoplan to compete on the market if it is approved.
In the Phase III trial patients who were anemic despite taking Soliris were randomized to receive either Soliris or pegcetacoplan. After 16 weeks the hemoglobin levels in the pegcetacoplan arm had increased by 3.8g/dL more than in the Soliris arm, exceeding the 2g/dL that Apellis was hoping for to demonstrate a meaningful difference. The trial also hit a key secondary endpoint with 85% of the pegcetacoplan arm transfusion-free at week 16 compared with only 15% of the Soliris arm. Many physicians regard being transfusion free as a key endpoint for PNH, indicating that pegcetacoplan could provide a particularly meaningful clinical benefit for patients.
Despite these positive trial results, there still remain several barriers that could prevent pegcetacoplan from being as successful as the results initially suggest. Firstly, there could be concerns over some of the side effects seen in the trial, with the rates of injection site reaction, diarrhea, and discontinuation higher in the pegcetacoplan arm of the trial. Furthermore, the FDA raised concerns over the apparent clinical benefit seen in the trial. The inclusion criteria for the trial allowed patients with high hemoglobin levels to enter the trial, and therefore the rise in hemoglobin levels seen in the trial might not actually lead to a clinical benefit.
Apellis plans to meet with the FDA and other regulatory agencies in the coming months to discuss the next steps required; it is possible that a further Phase III trial will be required, the results of which will prove pivotal in the eventual success or failure of pegcetacoplan.